Commutator truing tool



y 1937- c. M. BICKHAM ET AL 2,086,932

COMMUTATOR TRUING TOOL Filed June 3, 1955 gwuwv'cms (2 17/0215 MB Carson Tfiardceor'e/ Patented July 13, 1937 UNITED STATES PATENT OFFICE COMMUTATOR TRUING TooL Cliflord M. Bickham and Carson T. Hardacre, Hammond, Ind.

Application June 3, 1935, Serial No. 24,766

4 Claims. (Cl. 824

Our invention relates to the art of tools for a retaining pin 24 within the valve socket. A truing commutators, and has for an object the restricted bleeder groove 25 extends inwardly provision of a self-centering rotatable tool through the head from the ball valve seat, and adapted to be attached to the shafts of autoat its outer end the barrel l4 carries a cap nut mobile starter motors and generators, and which 26 threaded thereon and having a lateral stop is operable to true the commutators thereof. flange 21. Another object is the provision in such a tool of At its outer end the piston 20 is closed by a novel means for regulating the rate of speed at threaded plug 23 having an outwardly projecting which the work engaging element of the tool is axial hollow shank 29 which provides a support fed to the work. Other objects will become apfor the inn r r 0 of ball bearings 3| havin 10 parent from the description, to those skilled in their outer race 32 disposed Within a retaining the art. cup 33 detachably threaded as at 34 in the outer The present disclosure is illustrative of a preend of a hollow tube 35 concentric with the barrel ferred embodiment of 'the principles of our in- M and slidable axially thereon as W as being vention, and we desire it to be understood that rota e W respect thereto y Virtue 0f bear- 15 the invention is capable of all such changes in 111g S ve 35 Carried y the tube 35, as by a structural detail as will fall within the scope of S unk fit, which is slidable d otata p e i ve tion as claimed. In the drawing:-- the barrel i4, its extent of outward slidable move- Figure 1 is a longitudinal section through the m be g limited by engagement With the p tool as arranged for application in service poflange 2i at the outer end of the barrel. At its 20 sition. inner end 38 the tube 35 carries a fly wheel 31,

Figure 2 is a section on the line 2-2 of Figpreferably integral therewithure 1. Axially movable within the piston 20 is a float- Figure 3 is a section on the line 3 3 of Figs p r 39 h v an associated p Washer ure 1. 40. The plunger is normally forced inwardly 25 Figure 4 is a section on th line 4 .4 of Figunder the influence of an expansion spring 4! disure 1. 1 posed between the end plug 28 and the plunger. In Figure 1 the tool is shown as positioned for At the Outer end of the tool a drivel head 42 is operative engagement with the commutator l2 threaded into the outer end of the member 33, O of an automobile starter motor or generator, in being adapted o be t ed aga nst the Outer either of which the arm t shaft :3 extends ball race 32 to clamp it against the inner flange free. The tool comprises a hollow tubular barrel of the bearing cup member 33. The driver head M of uniform external diameter provided with an is axially bored and is 1 Ovided in its Outer face axial bore internally th t t inner or with a countersunk socket 43 cross-slotted as at work engaging end to receive the threaded seat M for Operative engagement with the pilot key end of a, chuck l5 perable in a known manner 35 mounted in the chuck 46 of a conventional by means of the chuck nut IE to engage over and drill 41.

make rigid connection with the end of the arma- The Wheel 37 Provides a tool 130$t portion ture shaft i3,whereby the barrel is centered upon 48 havlhg Set screw 49 by which the Shank n t d axially of t armature shaft 5% of a tool holder 5i is slidably adjustable in the 40 Substantially midway of the barrel the bore posh The holder 5! mounts a Work engaging hit enlarged to provide an Oil chamber H extend 52 adjustable in the holder in the conventional ing to the outer end of the barrel. This chammanner such h her is closed at its inner end by a seal plug Hi t the cna'mber H havmg, been having threaded seating engagement in the end P Wlth proper amount of the tool of the oil chamber and the chamber is supplied 15 attache? by means of the chuck so that the y barrel M is rigidly secured to and centered upon 1th fluid, preferably 011, through a filling port the armature shaft l3, as in Figure 1. The tool in the seal plug, the port being normally closed bit 52 is then adjusted for proper engagement by aflremovhble closhreelement with the work, the commutator segments, the '50 Axlahy Shdable Wlthlh the bore of the fluld tube 35 and its associated elements being moved c a fl its Outer end is a hollow axially over the barrel M for proper location of tubular p s 2 having a valved d 2| s atin the tool bit. Power is then applied to the driver an outwardly opening ball relief valve 22 mainhead 42 to rotate the tube 35 and its associated 55 tained on its seat by a coiled spring 23 held by tool bit mounting upon the barrel I4 and inward- 55 ly over the commutator segments. Any conventional electric or hand drill is used for power, with its pilot key operatively engaging the driver head to provide the power which acts not only to rotate the tool bit with respect to the commutator but also to feed the tool bit axially inward over the commutator at the same time. The ball bearings 3! and the sleeve bearing 36 insure free rotation of the driving member comprising the tube 35.

The speed at which the tool bit is fed to the work is maintained constant and steady by the compressing action of the piston upon the fluid in the chamber H as the piston is forced axially inward within the barrel M. The fluid discharges as a jet through the restricted bleeder groove of the piston head valve, entering the interior of the piston and maintaining a hydraulic back pressure, the relief of which controls the rate of tool feed with respect to the work. The fluid entering the hollow piston displaces the floating plunger 39 against compression of the spring ll.

When retracting the tool, the tube. is slid axially outward over the support barrel H3 until the outer end of the bearing sleeve 3% abuts the stop flange 2? on the cap nut 26. This movement carries the piston 20 outwardly, whereupon the external pressure upon the valve 22 is relieved, permitting the valve to open outwardly of the piston head for discharge of the piston contained fluid under the positive expelling action of the plunger 39 driven by the expansion of spring 4!.

The tool is adaptable for undercutting purposes, where the hydraulic governing means is not required. For such purposes the driver head 42 is removed, whereupon the tube 35 may be operated without imparting movement to the piston 20. The chuck l5 by reason of its detachable engagement with the support barrel is replaceable by similar chucks of different sizes, so that the tool is adaptable for use in connection with armature shafts of different diameters.

It is within the scope of our invention that the driven elements of the tool may be operated by the application of power from any suitable source or means and applied to any part of the assembly, although at present the application of an electric or hand drill to the driver head seems best suited to the purpose.

We claim:-

1. A commutator truing tool comprising an axially elongated cylindrical support, means for attaching said support rigidly to an armature shaft to extend axially therefrom, a member freely circumferentially rotatable and freely axially reciprocable on said support, a commutator engageable tool carried by said member and movable therewith, a fluid chamber in said support, and piston means fixedly connected with one end of said member and movable within said chamber to govern work engaging slidable movement of said member on the support.

2. A commutator truing tool comprising a tubular barrel, a chuck at one end thereof for rigid connection axially to an armature shaft, a tubular member slidable axially on the barrel and rotatable thereon, a commutator engageable tool carried by said member and movable therewith, said barrel having a bore providing a fluid chamber, a hollow piston associated with said tubular member and operable within said chamher by movement of said member whereby to compress fluid within the chamber upon work engaging movement of said member, and said piston having a restricted passage in its head to permit entry of fluid within the piston during work engaging travel of said tubular member.

3. A commutator truing tool comprising a tubular barrel, a chuck at one end thereof for rigid connection axially to an armature shaft, a tubular member slidable axially on said barrel and rotatable thereon, a commutator engageable tool carried by said member and movable therewith, said barrel having a bore provided with a fluid chamber, a hollow piston associated with said tubular member and operable within said chamber by movement of said member whereby to compress fluid in the chamber upon work engaging movement of said member, means for bleeding compressed fluid from the chamber to the interior of the piston during work engaging travel of said member, and means for expelling fluid from the piston to the chamber upon retractive travel of said member.

4. A commutator truing tool comprising an axially elongated cylindrical barrel open at one end and having in said end a chuck, an axially elongated sleeve freely slidable axially of the barrel and freely rotatable thereon, a tool mount on said sleeve, a member on said sleeve projecting axially within said barrel, and means in said barrel in cooperation therewith to regulate the speed of axial travel of said sleeve when moved axially over the barrel.

CLIFFORD M. BICKHAM. CARSON T. HARDACRE. 

